Spas with thermal pool

Scottsdale, Arizona

Andalusian-style resort spa at the base of Camelback Mountain with saunas, steam rooms, a hammam and three pools, open to guests 21 and up.

Edinburgh, Scotland

One Spa is an adults-only day spa in Edinburgh's city centre with a rooftop Hydropool, thermal suite and day-pass access.

St. Moritz, Grisons

An indoor-outdoor pool and spa complex in St. Moritz-Bad with four pools, three slides, a sauna zone, fitness center and bike/Nordic hub under one roof.

Pagosa Springs, Colorado

Victorian-style bathhouse in downtown Pagosa Springs with mineral soaking tubs, a rooftop tub, sauna, cold plunge and on-site massage.

Gothenburg, Västra Götaland County

A rooftop pool club and spa spanning two floors of the Jacy'z hotel in Gothenburg, with heated pools, sauna, steam room and a bar-restaurant, open for day

Buxton, England

Victorian hotel leisure club in Buxton with a heated indoor pool, gym, sauna and steam room, open to non-residents for an £8.50 day pass.

Mornington Peninsula, Victoria

Geothermal hot springs and day spa in Fingal on the Mornington Peninsula, with a family-friendly Bath House and an adults-only Spa Dreaming Centre.

Hot Springs, Arkansas

Thermal-water bathhouse on Central Ave in Hot Springs offering soaking pools, private mineral baths and eight spa treatments, minimum age 14.

Boston, Massachusetts

Hotel spa inside Raffles Boston pairing Guerlain facials and massages with a 65-foot lap pool, hot tub, sauna, steam room and three private treatment suites.

Scottsdale, Arizona

A hotel spa at JW Marriott Desert Ridge with sauna, steam rooms, a sanctuary pool, bistro and salon, open to day-pass guests as well as hotel guests.

Budapest

A centuries-old Turkish-style thermal bath on the Buda riverside with pools, saunas, massages and weekend late-night soaking hours.

Sirmione, Lombardy

A lakeside thermal spa in Sirmione with indoor and outdoor pools fed by sulphurous spring water, a vascular circuit, saunas, and a day-pass option.

Scuol, Grisons

Hotel spa at the 4-star Belvedere in Scuol with indoor/outdoor pools, mineral and thermal water, sauna, steam bath and a day pass option.

Palm Springs, California

Sante Spa is the adults-only resort spa at the Riviera Palm Springs, with 18 treatment rooms, a Watsu pool, steam room and validated valet parking.

Flúðir, Hrunamannahreppur

Iceland's oldest natural swimming pool, built in 1891 near Flúðir, fed entirely by onsite hot springs and a small geyser.

Sierraville, California

A non-profit hot springs retreat near Lake Tahoe with natural spring pools, reservation-only day and evening soaks, camping and rooms, closed Mondays and

Kyoto

Hotel spa in Kyoto's Higashiyama Ward with a day pass for pool, bathhouse, sauna and gym, plus treatment suites and couples options.

New York City, New York

Korean-style day spa in Edgewater, NJ, with saunas, thermal pools and an infinity pool, open daily 9am–9:30pm, day passes for walk-ins.

Sopot, Pomerania

A medical resort spa in Sopot built around local brine and mud treatments, open to hotel guests by reservation rather than day visitors.

Austin, Texas

Adults-only hotel spa at the Fairmont Austin with nine treatment rooms, a hydrotherapy circuit, sauna and cold plunge, open daily with day passes available.

Carmel-by-the-Sea, California

Resort spa at Carmel Valley Ranch with 12 treatment rooms, private terraces, a saltwater pool and infinity hot tub, open to adults by reservation.

New York City, New York

A budget-friendly Korean-style bathhouse in Queens with indoor and outdoor hydrotherapy pools, saunas and a restaurant, open to walk-ins daily.

Dallas, Texas

Korean-style day spa in Carrollton with hydrotherapy pools, saunas and relaxation lounges, open daily 9am–9:30pm with walk-in day passes.

Park City, Utah

A 27-room resort spa at Montage Deer Valley in Park City, open to hotel guests with a pool, steam room, sauna and cold plunge.